The present invention relates to an apparatus for the treatment of vegetation that includes a blower which is capable of producing a current of air, and means for atomising a treatment product in the current of air.
At present, apparatuses of this type which are found on the market are equipped with in axial or centrifugal blower, driven by the power take-off of a tractor by means of a mechanical transmission, or even by means of a hydraulic transmission comprising a pump, usually driven by the power take-off, and feeding a hydraulic engine by means of pipes under pressure.
It is even possible to find, although more rarely, blowers driven by an electric generator. Means, such as a gearbox, make it possible, in certain cases, to change when stationary the ratio between the speed of the power take-off of the tractor and the speed of rotation of the blower. Also found are blowers whose pitch can be changed when stationary.
When it is desired to treat plants, such as fruit trees, of a certain height, it is important that the output of the blower does not vary with the speed of the engine of the tractor. In the opposite case, there is a danger that the top of the trees will not be reached during slowing down and, on the contrary, that the air current will go too far during acceleration.
U.S. Pat. No. 4.609,145 in the name of Allen L. Miller describes a device which makes it possible to vary the speed of rotation of the blower of an apparatus for spreading pesticides, by virtue of a control located in the driver's cab, this control operating the feed valve of a hydraulic engine which operates the blower. Usually, the pressure of the feed fluid of a hydraulic engine mounted on a tractor is provided by a pump operated by the power take-off of the tractor. This means that, if the tractor has a reduction in speed, the output of the blower will be reduced also. It will thus be precisely at the moment when the driver of the tractor has to make a turn, for example, or face a difficulty, that the output of the blower will deviate from the value envisaged, and that it will be necessary, moreover, to monitor the speed of the latter. This arrangement, as can be seen, is not satisfactory.